Hydrogen evolution reaction (HER) at thin film and bulk TiC electrodes

The electrochemical behavior of titanium carbide in the form of sintered rod and thin film was investigated, in relation to the hydrogen evolution reaction (HER), in acidic and alkaline medium. The exchange current density, i 0 , and the charge transfer coefficient, α , were measured for the two types of cathode. In the case of sintered TiC, the i 0 values vary from ( 2.7 ± 0.4 ) × 10 - 6 (as measured in alkaline medium) to ( 3.5 ± 0.2 ) × 10 - 3 A m - 2 (as measured in acidic medium). This latter value (together with the α value) reveals that TiC cathodes are even more efficient than Pd in acid medium. Both types of TiC cathode are very stable in acid medium, also for prolonged electrolysis times. The study of the role played by the electroactive species concentration (i.e., [ H 3 O + ] or [ OH - ]), reveals that the sintered TiC cathode efficiency is higher at low acid concentration or in the presence of a supporting electrolyte. The minimum electric power necessary to drive the HER at a given rate is here evaluated.